<?php
//返回当前IP的城市字符串   
function convertip($ip) {
    //IP数据文件路径   
    $dat_path = ROOT_PATH.'./ip_area/area.Dat';   //修改成你服务器中地址
    //检查IP地址   
    if(!preg_match("/^(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])$/", $ip)) {   
        return 'IP Address Error';   
    }   
    //打开IP数据文件   
    if(!$fd = @fopen($dat_path, 'rb')){   
        return 'IP date file not exists or access denied';   
    }   
   
    //分解IP进行运算，得出整形数   
    $ip = explode('.', $ip);   
    $ipNum = $ip[0] * 16777216 + $ip[1] * 65536 + $ip[2] * 256 + $ip[3];   
   
    //获取IP数据索引开始和结束位置   
    $DataBegin = fread($fd, 4);   
    $DataEnd = fread($fd, 4);   
    $ipbegin = implode('', unpack('L', $DataBegin));   
    if($ipbegin < 0) $ipbegin += pow(2, 32);   
    $ipend = implode('', unpack('L', $DataEnd));   
    if($ipend < 0) $ipend += pow(2, 32);   
    $ipAllNum = ($ipend - $ipbegin) / 7 + 1;   
       
    $BeginNum = 0;   
    $EndNum = $ipAllNum;   
   
    //使用二分查找法从索引记录中搜索匹配的IP记录   
    while($ip1num>$ipNum || $ip2num<$ipNum) {   
        $Middle= intval(($EndNum + $BeginNum) / 2);   
   
        //偏移指针到索引位置读取4个字节   
        fseek($fd, $ipbegin + 7 * $Middle);   
        $ipData1 = fread($fd, 4);   
        if(strlen($ipData1) < 4) {   
            fclose($fd);   
            return 'System Error';   
        }   
        //提取出来的数据转换成长整形，如果数据是负数则加上2的32次幂   
        $ip1num = implode('', unpack('L', $ipData1));   
        if($ip1num < 0) $ip1num += pow(2, 32);   
           
        //提取的长整型数大于我们IP地址则修改结束位置进行下一次循环   
        if($ip1num > $ipNum) {   
            $EndNum = $Middle;   
            continue;   
        }   
           
        //取完上一个索引后取下一个索引   
        $DataSeek = fread($fd, 3);   
        if(strlen($DataSeek) < 3) {   
            fclose($fd);   
            return 'System Error';   
        }   
        $DataSeek = implode('', unpack('L', $DataSeek.chr(0)));   
        fseek($fd, $DataSeek);   
        $ipData2 = fread($fd, 4);   
        if(strlen($ipData2) < 4) {   
            fclose($fd);   
            return 'System Error';   
        }   
        $ip2num = implode('', unpack('L', $ipData2));   
        if($ip2num < 0) $ip2num += pow(2, 32);   
   
        //没找到提示未知   
        if($ip2num < $ipNum) {   
            if($Middle == $BeginNum) {   
                fclose($fd);   
                return 'Unknown';   
            }   
            $BeginNum = $Middle;   
        }   
    }   
   
    $ipFlag = fread($fd, 1);   
    if($ipFlag == chr(1)) {   
        $ipSeek = fread($fd, 3);   
        if(strlen($ipSeek) < 3) {   
            fclose($fd);   
            return 'System Error';   
        }   
        $ipSeek = implode('', unpack('L', $ipSeek.chr(0)));   
        fseek($fd, $ipSeek);   
        $ipFlag = fread($fd, 1);   
    }   
   
    if($ipFlag == chr(2)) {   
        $AddrSeek = fread($fd, 3);   
        if(strlen($AddrSeek) < 3) {   
            fclose($fd);   
            return 'System Error';   
        }   
        $ipFlag = fread($fd, 1);   
        if($ipFlag == chr(2)) {   
            $AddrSeek2 = fread($fd, 3);   
            if(strlen($AddrSeek2) < 3) {   
                fclose($fd);   
                return 'System Error';   
            }   
            $AddrSeek2 = implode('', unpack('L', $AddrSeek2.chr(0)));   
            fseek($fd, $AddrSeek2);   
        } else {   
            fseek($fd, -1, SEEK_CUR);   
        }   
   
        while(($char = fread($fd, 1)) != chr(0))   
            $ipAddr2 .= $char;   
   
        $AddrSeek = implode('', unpack('L', $AddrSeek.chr(0)));   
        fseek($fd, $AddrSeek);   
   
        while(($char = fread($fd, 1)) != chr(0))   
            $ipAddr1 .= $char;   
    } else {   
        fseek($fd, -1, SEEK_CUR);   
        while(($char = fread($fd, 1)) != chr(0))   
            $ipAddr1 .= $char;   
   
        $ipFlag = fread($fd, 1);   
        if($ipFlag == chr(2)) {   
            $AddrSeek2 = fread($fd, 3);   
            if(strlen($AddrSeek2) < 3) {   
                fclose($fd);   
                return 'System Error';   
            }   
            $AddrSeek2 = implode('', unpack('L', $AddrSeek2.chr(0)));   
            fseek($fd, $AddrSeek2);   
        } else {   
            fseek($fd, -1, SEEK_CUR);   
        }   
        while(($char = fread($fd, 1)) != chr(0)){   
            $ipAddr2 .= $char;   
        }   
    }   
    fclose($fd);   
   
    //最后做相应的替换操作后返回结果   
    if(preg_match('/http/i', $ipAddr2)) {   
        $ipAddr2 = '';   
    }   
    $ipaddr = "$ipAddr1 $ipAddr2";   
    $ipaddr = preg_replace('/CZ88.Net/is', '', $ipaddr);   
    $ipaddr = preg_replace('/^s*/is', '', $ipaddr);   
    $ipaddr = preg_replace('/s*$/is', '', $ipaddr);   
    if(preg_match('/http/i', $ipaddr) || $ipaddr == '') {   
        $ipaddr = 'Unknown';   
    }   
   
    return $ipaddr;   
}
//查找字符串   
function findstr($str, $substr)   
{
         $m = strlen($str);   
        $n = strlen($substr );   
        if ($m < $n) return false ;   
        for ($i=0; $i <=($m-$n+1); $i ++){   
                $sub = substr( $str, $i, $n);   
                if ( strcmp($sub, $substr) == 0) return true;   
        }   
        return false ;   
}
?>